US8248326B2 - Image display apparatus and manufacturing method thereof - Google Patents
Image display apparatus and manufacturing method thereof Download PDFInfo
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- US8248326B2 US8248326B2 US12/335,968 US33596808A US8248326B2 US 8248326 B2 US8248326 B2 US 8248326B2 US 33596808 A US33596808 A US 33596808A US 8248326 B2 US8248326 B2 US 8248326B2
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2300/00—Aspects of the constitution of display devices
- G09G2300/04—Structural and physical details of display devices
- G09G2300/0421—Structural details of the set of electrodes
- G09G2300/0426—Layout of electrodes and connections
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2300/00—Aspects of the constitution of display devices
- G09G2300/04—Structural and physical details of display devices
- G09G2300/0439—Pixel structures
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0209—Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0285—Improving the quality of display appearance using tables for spatial correction of display data
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/2007—Display of intermediate tones
- G09G3/2014—Display of intermediate tones by modulation of the duration of a single pulse during which the logic level remains constant
Definitions
- the present invention relates to an image display apparatus and a manufacturing method thereof.
- halation emission occurs in an image display apparatus using an electron beam.
- an electron emitted from an electron source collides with a phosphor, the phosphor emits light. At this time, not only occurs the light emission of the phosphor but also scattering of electrons occurs ( FIG. 3A ). Backward scattered electrons scattered around the phosphor by scattering cause peripheral phosphors to emit light. This light emission is called halation emission.
- JP-A No. 2006-047987 describes a configuration that corrects influence of halation emission occurring at peripheral pixels by light emission from luminescent spot in an electron beam display apparatus.
- Japanese Patent Application No. 3870210 (JP-A No. 2006-171502) and Japanese Patent Laid-Open (JP-A) No. 2006-195444 describe configurations that perform adjustment using a values depending on an emission color in an emitting region to reduce deterioration in halation.
- JP-A No. 2006-195444 describes, in particular, a configuration that adjusts an amount of correction by using an adjusted value predetermined for each color or an adjusted value which can be dynamically changed in units of colors depending on a lighting pattern of original image data.
- the present inventors had an image displayed on image display apparatuses with the conventional correction method, and checked spacer unevenness caused by halation emission. As a result, the present inventors found degrees of correction for reducing difference of chromatic purity and luminance varies between pixels proximate to spacers and pixels not proximate to spacers.
- the present invention provides an image display apparatus having:
- a face plate with a plurality of light-emitting regions
- the drive circuit has a correction circuit that calculates a correction value evaluated by influence of emitted electrons from electron-emitting devices which correspond to light-emitting regions around the light-emitting region to be corrected, and corrects a signal input to the electron-emitting device corresponding to the light-emitting region to be corrected based on the correction value, and
- the correction circuit has an adjustment circuit that adjusts the correction value based on variation of characteristics of the plurality of light-emitting regions.
- the present invention provides an image display apparatus having:
- a face plate with a plurality of light-emitting regions
- the drive circuit has a correction circuit that calculates a correction value evaluated by influence of emitted electrons from proximate electron-emitting devices which correspond to light-emitting regions around the light-emitting region to be corrected, and corrects a signal input to the electron-emitting device corresponding to the light-emitting region to be corrected based on the correction value, and
- the correction circuit has an adjustment circuit that adjusts the correction value based on variation of electron-emitting characteristics of the adjacent electron-emitting devices.
- the present invention provides a manufacturing method for an image display apparatus comprising a face plate with a plurality of light-emitting regions, a rear plate with electron-emitting devices corresponding to the plurality of light-emitting regions, respectively, and a drive circuit that drives the electron-emitting devices, wherein the drive circuit has a correction circuit that calculates a correction value evaluated by influence of emitted electrons from electron-emitting devices which correspond to light-emitting regions around the light-emitting region to be corrected, on the light-emitting region to be corrected, and corrects a signal input to the electron-emitting device corresponding to the light-emitting region to be corrected based on the correction value with adjustment according to variation of characteristics of the plurality of light-emitting regions, the method comprising the steps of:
- the present invention provides a manufacturing method for an image display apparatus comprising a face plate with a plurality of light-emitting regions, a rear plate with electron-emitting devices corresponding to the light-emitting regions, respectively, and a drive circuit that drives the electron-emitting devices, wherein the drive circuit has a correction circuit that calculates a correction value evaluated by influence of emitted electrons from proximate electron-emitting devices which correspond to light-emitting regions around the light-emitting region to be corrected, on the light-emitting region to be corrected, and corrects a signal input to the electron-emitting device corresponding to the light-emitting region to be corrected based on the correction value with adjustment according to variation of electron-emitting characteristics of the proximate electron-emitting devices, the method comprising the steps of:
- an image display apparatus having lesser display unevenness by improving correction performance.
- FIG. 1 is a diagram showing a configuration of a halation correction circuit
- FIGS. 3A and 3B are diagrams for explaining a halation occurrence mechanism at a position adjacent to a spacer
- FIGS. 4A and 4B are diagram for explaining a halation occurrence mechanism at a position unadjacent to a spacer
- FIG. 5 is an 11 ⁇ 11-halation mask pattern diagram
- FIGS. 6A and 6B are diagrams for explanation of halation correction performed by a blocked amount adding scheme
- FIG. 7 is a corresponding diagram of pixels where reflected electrons are blocked depending on distances between target pixels and spacers;
- FIG. 8 is a schematic diagram showing a relationship between a phosphor aperture ratio and a halation emission luminance
- FIG. 9 is a diagram showing configurations of pixel adjustment calculating units A and B;
- FIG. 10 is a diagram showing configurations of the pixel adjustment calculating units A and B when an adjusted value depending on an input signal is used;
- FIG. 11 is a schematic diagram showing a relationship between an electron scattering efficiency and a halation emission luminance on a phosphor
- FIG. 12 is a diagram showing a relationship between a fluctuation in current in constant-voltage drive and a halation luminance when a luminance is made constant by giving a drive time difference to the fluctuation in current;
- FIG. 13 is a diagram showing a schematic configuration of a display panel.
- a screen is configured by a plurality of pixels.
- Each of the pixels has a light-emitting region having any one of several different colors, particularly red (R), green (G), and blue (B), as a light-emitting color.
- Phosphors which emit light by irradiation of electrons are used as light-emitting members constituting the light-emitting region.
- a pixel having a red light-emitting region, a pixel having a green light-emitting region, and a pixel having a blue light-emitting region are combined to each other, so that a visual neutral color display is realized by controlling emission amount of the respective colors.
- Each of the pixels has an electron-emitting device corresponding to each of the light-emitting regions.
- a surface conduction electron-emitting device display (SED display apparatus) is employed.
- the present invention includes other field emission display (FED display apparatus). These image display apparatuses are preferred embodiments to which the present invention is applied because halation emission may occur on peripheral pixels due to light emission from luminescent spot which is selfluminant.
- the display panel 25 shown in FIG. 13 has electron-emitting devices and light-emitting members.
- electron-emitting devices In the embodiment described here, as particularly preferable electron-emitting devices, surface conduction electron-emitting devices 4004 are used.
- spint type electron-emitting devices having an emitter cone and a gate electrode combined, electron-emitting devices using carbon fibers such as carbon nanotubes or graphite nanofibers, MIM type electron-emitting devices, and the like can be employed.
- the embodiment employs a configuration in which the plurality of surface conduction electron-emitting devices 4004 are connected in the form of a matrix by a plurality of scan signal applying lines 4002 and modulated signal applying lines 4003 .
- Scan signals output from a row-line switch unit 23 are sequentially applied to the scan signal applying lines 4002 .
- Modulated signals output from the column-line switch unit 21 are applied to the modulated signal applying lines 4003 .
- the electron-emitting devices, the scan signal applying lines, and the modulated signal applying lines, the lines being connected to the electron-emitting devices in the form of a matrix are arranged on a rear plate 4005 .
- a phosphor 4008 is used as a light-emitting member.
- the phosphor 4008 is arranged on a face plate 4006 .
- a metal back 4009 serving as an accelerating electrode to accelerate electrons emitted from the electron-emitting device is arranged on the face plate 4006 .
- An accelerating potential is supplied from a high-voltage power supply 24 to the metal back 4009 through a high-voltage terminal 4011 .
- a glass frame 4007 serving as an outer frame is located between the rear plate 4005 and the face plate 4006 , and the rear plate 4005 and the glass frame 4007 are air tightly sealed, and the face plate 4006 and the glass frame 4007 are also air tightly sealed.
- an airtight container is configured by the rear plate 4005 , the face plate 4006 , and the glass frame 4007 .
- the interior of the airtight container is kept in a vacuum state.
- Spacers 4012 are arranged in the airtight container, thereby the airtight container is prevented from being collapsed by a pressure difference between the inside of the airtight container and the outside thereof.
- FIG. 13 only one spacer 4012 is illustrated. However, in fact, a plurality of spacers are arranged at intervals of several ten lines.
- a position on the panel almost facing an electron-emitting device is a light-emitting region (light-emitting member) corresponding to the electron-emitting device.
- FIG. 2 is a circuit diagram of a drive unit of the image display apparatus according to the embodiment.
- An input video signal S 1 is subjected to signal processing suitable for a display through a signal processing unit 13 , and is output as a display signal S 2 .
- As functions of the signal processing unit 13 in FIG. 2 only required minimum functional blocks are described in the explanation of the embodiment.
- an input video signal S 1 on the premise of being displayed on CRT, is subjected to nonlinear conversion such as 0.45-power conversion called gamma conversion matched with an input-emission characteristic of a CRT display and then transmitted or recorded.
- an input signal When the video signal is displayed on a display device such as an SED, an FED, or a PDP having a linear input-emission characteristic, an input signal must be subjected to an inverse gamma conversion such as 2.2-power conversion. More specifically, an inverse- ⁇ -correcting unit 14 converts an input video signal into data which is linear with respect to a luminance. An output from the inverse- ⁇ -correcting unit 14 is input to a halation correcting unit 15 serving as a characteristic feature of the embodiment. The halation correcting unit 15 will be described below in detail. An output from the halation correcting unit 15 serves as an input to a BIT correcting unit 16 .
- the BIT correcting unit uniforms the maximum luminance to a predetermined luminance value in order to eliminate a variation in light emission caused by an electron source and a phosphor.
- An output from the BIT correcting unit serves as an input to a phosphor saturation correcting unit 17 which adjusts an input to make it possible to accurately display output colors and contrast in consideration of gamma characteristics of R, G, and B phosphors.
- An output from the phosphor saturation correcting unit 17 is output as the video display signal S 2 suitable for an SED.
- a timing control unit 18 generates and outputs various timing signals for operations of the blocks based on a synchronous signal transferred together with the input video signal S 1 .
- a PWM pulse control unit 19 converts the display signal S 2 into a drive signal (for example, PWM modulation) suitable for the display panel 25 every horizontal scan cycle (row selection period).
- a drive voltage control unit 20 controls a voltage that drives the devices arranged on the display panel 25 .
- the column-line switch unit 21 is configured by switch units such as transistors, and applies a drive output from the drive voltage control unit 20 to modulation lines during PWM pulse period, in which the PWM pulse control unit 19 outputs PWM pulse, every horizontal scan cycle (row selection period).
- a row selection control unit 22 generates a row selection pulse that drives the devices on the display panel.
- the row-line switch unit 23 is configured by switch units such as transistors, and outputs a drive output from the drive voltage control unit 20 , which output accords to a row selection pulse output from the row selection control unit 22 , to the display panel 25 .
- a high-voltage power supply 24 generates an accelerating voltage that accelerates electrons emitted from the electron-emitting device arranged on the display panel 25 to cause the electrons to collide with the phosphor. In this manner, the display panel 25 is driven to display a video image.
- the drive circuit includes the signal processing unit 13 , the PWM pulse control unit 19 , the drive voltage control unit 20 , the column-line switch unit 21 , the row selection control unit 22 , and the row-line switch unit 23 .
- the halation correcting unit 15 which is a characteristic feature of the present invention will be described below with reference to FIG. 1 . Prior to the explanation of FIG. 1 , what halation is will be described below.
- FIG. 3A shows an image display apparatus in which electron-emitting devices are formed on the rear plate and light-emitting members (in the embodiment, red, blue, and green phosphors) are arranged on the face plate with space between the light-emitting members and the electron-emitting devices.
- electron beams primary electrons
- emitted from the electron-emitting devices are irradiated on corresponding light-emitting members to emit light.
- color reproducibility is different from color reproducibility in the desired state.
- blue color light not pure blue color but light having a color slightly mixed with other colors, that is, light in which green and red colors are mixed is emitted, with poor color saturation.
- the present inventors figured out the cause of the deterioration of chroma saturation. This cause is as follows. Primary electrons emitted from an electron-emitting device impinge on the corresponding light-emitting member so that the light-emitting member may emit light at its luminescent spot. But these primary electrons are reflected by the light-emitting member and impinge on close (and proximate) light-emitting regions of different colors as backward scattered electrons (reflected electrons, secondary electrons). The backward scattered electrons cause peripheral light-emitting members to emit light, thereby deteriorating chroma saturation.
- halation A phenomenon that a display device emits light by an influence from the drive of adjacent display devices, such as light emission due to reflected electrons, is referred to as “halation” in the present specification.
- SED SED
- FIG. 3B it was found that, when electrons are irradiated on a certain phosphor, halation causes circular light emission around the pixel (light emission is distributed in a cylinder around the luminescent spot if expressed in terms of brightness as a quantity of emitted light). If a radius of this circular region influenced by halation is as long as n number of pixels, a filter as large as (2n+1) number of taps is required as pixel reference range for a halation correction process, which will be described in detail later.
- the radius of the region to which the halation extends is a static parameter obtained from a physical structure (interval between the face plate and the rear plate and pixel size). Therefore, when the same correcting circuit is caused to cope with different SED panels of a plurality of types, a halation mask pattern in FIG. 5 should be changeable as a variable parameter.
- FIGS. 3A and 3B show a case where there is no blocking member such as a spacer on a reflecting path of reflected electrons (not in the vicinity of a spacer).
- a blocking member such as a spacer
- backward scattered electrons reflected electrons or secondary electrons
- FIG. 4A backward scattered electrons
- halation strength is reduced.
- 3A and 4A show R, G, and B phosphors alternately arranged ⁇ lateral stripes> in a line direction.
- the R, G, and B phosphors are alternately arranged ⁇ longitudinal stripes> in a horizontal direction.
- the above operation is an occurrence mechanism of halation explained by using a light-emitting state obtained by one device as an example.
- plural long spacers are mounted at intervals of several ten lines, extending in a lateral direction.
- the halation causes a difference between amounts of halation at a position proximate to the spacer and a position not proximate to the spacer. It was confirmed that the difference in quantity of halation causes an inherent problem that color purity changes in the vicinity of the spacer. This problem is referred to as spacer unevenness.
- spacer unevenness A degree of spacer unevenness varies with a lighting pattern of a display image.
- halation luminance is added to blue-light-emitting luminance. Since, at the position proximate to the spacer, an amount of blocking of reflected electrons gradually changes depending on distances from the spacer, a wedge-shaped gradual change in color purity in a range of about 10 lines is visually recognized.
- FIG. 1 is a diagram showing a detailed configuration of the halation correcting unit 15 .
- Image data inverse- ⁇ -converted and input to the halation correcting unit 15 is converted into data of a format in which an amount of halation emission can be calculated and then given to a line memory 1 .
- the format converting process is performed by an L-PW table (luminance-pulse width table) 9 .
- L-PW table luminance-pulse width table
- phosphors have such light-emitting characteristics that an increase rate of the light-emitting luminance decreases when an irradiation time of a beam is longer or when the beam is stronger. Due to the presence of the phenomenon, the L-PW table 9 is needed.
- the line memory 1 includes 11 line memories in the embodiment.
- Original image data are sequentially written in the line memory 1 in units of lines.
- the data of the 11 lines are stored, the data of 11 pixels ⁇ 11 lines are simultaneously read for calculation.
- the data of 11 pixels ⁇ 11 lines around a target pixel simultaneously read are referred for an arithmetic operation by a selective addition unit 2 , and data of the target pixel are given to a correction addition unit 7 .
- the selective addition unit 2 selectively adds the number of electrons blocked by a spacer among the reflected electrons from pixels around the target pixel, to data of the target pixel proximate to the spacer. It is determined by an SPD (Spacer Distance) value whether the target pixels are at the position proximate to the spacer. This SPD value indicates a positional relationship between the target pixel and the spacer, and is generated by a spacer position information generating unit 4 based on a timing control signal and spacer position information received from the timing control unit 18 .
- SPD Spacer Distance
- the target pixel in the vicinity of the spacer there are ten patterns, depending on the SPD value, of the pixels to which the reflected electrons can not reach due to blocking by the spacer.
- a total amount of lighting related to an amount of blocking can be calculated by selecting pixel values indicated in gray depending on the SPD value and adding the pixel values.
- Each pixel has red (R), green (G), and blue (B) light-emitting regions.
- the input signals are input as an R signal, a G signal, and a B signal corresponding to each pixel.
- a coefficient multiplication unit 3 multiplies the addition result by a coefficient (halation gain value) representing a percentage of blocked electrons that would contribute to halation.
- the coefficient falls in the range of 0 to 1, in general. In an actual panel, the coefficient is a value of about 1.5%.
- Data output from the coefficient multiplication unit 3 is an amount of light emission blocked by a spacer, i.e., an amount of halation emission to be added if no spacer is present.
- the amount of blocking of the halation emission corresponds to influence of electrons emitted from the proximate electron-emitting devices on the light-emitting region to be corrected in the present invention.
- Data output from the coefficient multiplication unit 3 corresponds to a correction value calculated by evaluating the influence of the electrons emitted from the proximate electron-emitting devices on the light-emitting region to be corrected in the present invention. As described above, the value is obtained by evaluating image data corresponding to all of the colors at once.
- an adjusting gain multiplication unit 5 multiplies correction data calculated through the coefficient multiplication unit 3 by one of conversion coefficients depending on the R, G, and B phosphors, which coefficients can be obtained from a conversion coefficient calculating unit 8 . Thereby, adjustment of an amount of correction is performed.
- the conversion coefficient can be selected in consideration of an input image signal (lighting pattern) of pixels to be corrected.
- correction data of an output from the coefficient multiplication unit 3 is converted into an optimum amount of correction according to the phosphor types of the pixels to be corrected.
- the correction addition unit 7 adds the adjusted correction amount thus obtained to original image data, and outputs the result as a correction image.
- a correction value corresponding to blocked amount by the spacer of halation of reflected electrons is added, and a difference between color purities at positions proximate and non-proximate to the spacer is reduced in an entire screen. More specifically, as shown in FIG. 6A , a gradual change in color purity occurring at the position adjacent to the spacer before the correction is suppressed by the above correction as shown in FIG. 6B . In this manner, space unevenness caused by halation can be corrected.
- the present inventors operate an actual SED panel by using the correcting method described above to evaluate its effect, the present inventors found that degrees of correction reducing differences in color purity and luminance at the position unadjacent to the spacer and the position adjacent to the spacer, varies with pixels. More specifically, it was found that when adjustment of the correction value is performed with overall lighting, overcorrected pixels and undercorrected pixels are generated, and some pixel needs unique adjustment to the correction values. The overcorrection and the undercorrection mean that variation of characteristics between pixels exceeds an allowable margin of error for spacer unevenness.
- a configuration is employed, in which not only a correction amount is adjusted depending on phosphor types of the pixels but also adjustment of the amount of correction is performed in consideration of the variation in characteristic of the pixels.
- a pixel adjustment multiplication unit A 6 and a pixel adjustment multiplication unit B 10 are arranged as subsequent parts of the L-PW table 9 and the conversion coefficient calculating unit 8 . In either or both the pixel adjustment multiplication unit A and the pixel adjustment multiplication unit B, adjustment depending on a variation in pixel characteristic is performed.
- the pixel adjustment multiplication unit A 6 and the pixel adjustment multiplication unit B 10 correspond to the adjustment circuits according to the present invention.
- the L-PW table 9 and the pixel adjustment multiplication unit A 6 may be mounted as one circuit, and adjustment may be performed by the L-PW table 9 .
- the conversion coefficient calculating unit 8 and the pixel adjustment multiplication unit B 10 may be mounted as one circuit, and adjustment may be performed by the conversion coefficient calculating unit 8 .
- An amount of halation emission is determined by two factors, that is, a factor of how much electrons are scattered at an irradiated phosphor and impinges on a peripheral phosphor and a factor of how much light emission occurs when a certain number of scattered electrons impinges on the phosphor. More specifically, each of the pixels has two roles: one is a role as a pixel (electron scattering pixel) which scatters electrons from an electron source; and the other is a role as a pixel (halation emission pixel) on which scattered electrons impinges.
- both the difference between pixels serving as electron scattering pixels and the difference between pixels serving as halation emission pixels can be corrected.
- only one of the difference between the pixels serving as the electron scattering pixels and the difference between the pixels serving as the halation emission pixels is corrected, only corresponding one of the adjustment circuits is employed.
- the pixel adjustment multiplication unit includes a circuit which outputs an adjusted value according to a pixel address and a multiplying unit which multiplies the adjustment value, and multiplies an input signal by the adjustment value according to a pixel address of an input video signal to output a resultant signal.
- a circuit which outputs an adjustment value according to a pixel address includes a LUT (Look-Up table) having differences of the adjustment values from an offset value and an addition circuit which adds the offset value.
- LUT Look-Up table
- a variation in characteristic of the pixels in particular, any one of a phosphor and an electron-emitting device
- the offset value is set to 1.
- the LUT corresponds to a memory unit in the present invention.
- the pixel adjustment multiplication unit A 6 and the pixel adjustment multiplication unit B 10 adjust a correction value depending on a variation in pixel characteristics.
- the conversion coefficient calculating unit 8 adjusts a correction value depending on the types of phosphors of pixels.
- adjustment values are determined while giving attention to difference of phosphor aperture ratios of the pixels as difference of pixel characteristics.
- the aperture ratio of the phosphor is a ratio ((phosphor region)/(phosphor region+non-phosphor region) ) of a phosphor region to a sum of the phosphor region and a non-phosphor region in one pixel (picture element).
- the aperture ratio is defined as a ratio of an area in which the phosphor is exposed without black matrix or the like to the entire area of one pixel.
- the halation emission luminance is in proportion to a phosphor aperture ratio ( FIG. 8 ). For this reason, even though the backward scattered electrons are uniformly distributed, the halation emission luminance changes due to the aperture ratios of the phosphors.
- values being in proportion to the phosphor aperture ratios are used as an adjustment values.
- Kav an average of the phosphor aperture ratios of all the pixels
- K/Kav an adjustment value for a pixel having a phosphor aperture ratio K is given by K/Kav.
- the adjustment value corresponding to each of the pixels is determined based on a ratio of an aperture ratio of a corresponding phosphor to the overall average (that is, a variation in phosphor aperture ratio). Since a change in halation emission luminance caused by the phosphor is a characteristic of a halation emission pixel, the adjustment is performed by the pixel adjustment multiplication unit B.
- a method of manufacturing an image display apparatus will be described below.
- Black matrix regions are formed on a glass substrate serving as a face plate, and phosphors are coated on the glass substrate between the black matrixes and then calcined to form light-emitting regions.
- This step is performed such that ratios of phosphor region to black matrix region are equal in all pixels. In actual manufacturing, errors occur.
- phosphor aperture ratios of all the pixels are measured by photographing each light-emitting region and analyzing the images.
- Aperture ratio K of each of the phosphors is associated with the pixel address and stored in the LUT in form of ratio K/Kav to the average Kav of all the pixels. In this manner, the image display apparatus according to the embodiment is manufactured.
- an adjustment value is determined while giving attention to difference of electron scattering efficiencies of phosphors in pixels as difference of pixel characteristics.
- the film thicknesses in all the pixels are designed to be equal, the film thicknesses may slightly varies in an actual manufacturing step.
- the film thicknesses of phosphors and metal backs vary in the manufacturing step, the numbers of electrons scattered by the phosphors of the pixels are different from each other.
- halation luminance of the pixels differ among the pixels.
- halation emission luminance is in proportion to electron scattering efficiency ( FIG. 11 ).
- adjustment values values being in proportion to the electron scattering efficiency are used.
- an average of electron scattering efficiencies in the phosphors of all the pixels is given by Lav
- an adjustment value for a pixel having a scattering efficiency L is given by L/Lav. Since a change inhalation emission luminance caused by the electron scattering efficiency in the phosphor is a characteristic of an electron scattering pixel, adjustment is performed by the pixel adjustment multiplication unit A 6 .
- the image display apparatus can be manufactured as follows. After the step of forming light-emitting regions on a face plate, electrons are irradiated on an arbitrary pixel. Peripheral halation emission luminance caused by scattered electrons from the pixel is measured. Measuring light-emitting characteristics of phosphors of the peripheral pixels in advance, the number of scattered electrons from the pixel can be calculated from the halation emission luminance. Therefore, an electron scattering efficiency of an Interested pixel can be measured. The electron scattering efficiencies of all the pixels are measured in the same way, and a ratio L/Lav of a scattering efficiency L of each pixel to an average Lav of all the pixels is stored in an LUT in association with a pixel address. In this manner, the image display apparatus according to the embodiment is manufactured.
- an adjustment value is determined in consideration of a difference of I-V (the number of emitted electrons—applied voltage) characteristics (electron emitting characteristics) of electron-emitting devices as a difference between pixel characteristics.
- the characteristics of all the electron-emitting devices are designed to be equal, the characteristics slightly vary in an actual manufacturing step.
- the number of electrons emitted when a constant voltage is applied may thus vary.
- emission currents vary with the electron-emitting devices even if a constant voltage is applied to electron-emitting devices
- different halation luminance may be obtained due to a relationship between luminance saturation characteristics to time of the phosphors and luminance saturation characteristics to current density. More specifically, even though a certain number of electrons are irradiated as whole, the halation luminance varies if emission current densities and electron-emitting times vary. For example, emission luminance will be different between when electrons with high emission current density are irradiated for a short period of time and when electrons with low emission current density are irradiated for a long period of time.
- Emission characteristic L f(Ie, PW) of the phosphor with respect to electron source drive time PW and emission current Ie of the phosphor is obtained by measuring emission for various combinations of PW and Ie. In this case, it is assumed that only the electron-emitting devices vary and the phosphors do not vary, and thus the emission characteristics L are assumed to be equal for all the phosphors.
- a drive time must be set to PW 0 in order for a pixel having an emission current Ie 0 to satisfy a luminance L 0 , where the luminance L 0 is determined by a signal level of input image data.
- incident density of electrons diffused by phosphor is 0.00007*Ie 0
- a change in halation emission luminance caused by the electron source I-V characteristic depends on times for which emission currents Ie, which is different for all the electron-emitting devices, are emitted. Since the characteristic is a characteristic of the electron scattering pixel, the halation emission luminance is adjusted by the pixel adjustment multiplication unit A 6
- the adjustment value Lh/Lhav may also depend on a signal level of image data. In this case, the configuration of the pixel adjustment multiplication unit A 6 is so modified that adjustment value depends not only on pixel address but on both pixel address and signal level of the image data (the configuration is shown in FIG. 10 ), thereby making it possible to perform accurate correction in various signal level.
- This configuration can be employed when, for example, characteristics of aperture ratios at a central portion and a peripheral portion on the face plate are different from each other due to a method of manufacturing a phosphor.
- the same value is employed as an adjustment value in the same region.
- the tendencies of the aperture ratio characteristics in the different regions change depending on manufacturing methods, a place having almost constant phosphor aperture ratios is sectioned as one region.
- K 0 /Kave is applied as an adjustment value to all the pixels in the section.
- the same adjustment value can be shared by a plurality of pixels. For this reason, an image display apparatus having lesser display unevenness can be provided with a small memory capacity.
- halation correction halation luminance that would be generated when spacers was absent is calculated, and emission of halation-blocked light-emitting region blocked by the spacer is compensated by an amount of the blocking.
- a halation emission luminance that would be generated if spacers was not used is calculated, which halation emission luminance is caused by electrons blocked by a spacer among electrons irradiated from the proximate electron-emitting devices and scattered at peripheral light-emitting regions.
- Correction is performed to add the blocked halation emission luminance to a luminance to be corrected. In the correcting method, correction is performed such that uniform halation emission occurs in all the pixels.
- the halation correcting method is not limited to the above method.
- correction may be performed to suppress halation emission in all the pixels.
- a halation emission luminance actually generated is calculated, which halation emission luminance is caused by electrons irradiated from the proximate electron-emitting devices and scattered at the peripheral light-emitting regions.
- Correction is performed such that the halation emission luminance is subtracted from the light-emitting region to be corrected.
- a method of measuring correction errors of pixels after a conventional correcting method is executed and determining an adjustment value to cancel overs and shorts can be performed.
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- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
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Abstract
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JP2007326213A JP2009150926A (en) | 2007-12-18 | 2007-12-18 | Image display apparatus and manufacturing method thereof |
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US20110181587A1 (en) * | 2010-01-22 | 2011-07-28 | Sony Corporation | Image display device having imaging device |
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US20050286062A1 (en) | 2004-06-29 | 2005-12-29 | Canon Kabushiki Kaisha | Correction circuit |
US20060132394A1 (en) | 2004-12-17 | 2006-06-22 | Canon Kabushiki Kaisha | Image display apparatus and television apparatus |
US20060132396A1 (en) | 2004-12-17 | 2006-06-22 | Canon Kabushiki Kaisha | Image display apparatus |
US7230386B2 (en) * | 2004-06-29 | 2007-06-12 | Canon Kabushiki Kaisha | Image display apparatus |
US7298094B2 (en) * | 2005-12-28 | 2007-11-20 | Canon Kabushiki Kaisha | Image display apparatus |
US20080150842A1 (en) | 2006-12-25 | 2008-06-26 | Canon Kabushiki Kaisha | Image display apparatus |
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US20050286062A1 (en) | 2004-06-29 | 2005-12-29 | Canon Kabushiki Kaisha | Correction circuit |
JP2006047987A (en) | 2004-06-29 | 2006-02-16 | Canon Inc | Correction circuit |
US7230386B2 (en) * | 2004-06-29 | 2007-06-12 | Canon Kabushiki Kaisha | Image display apparatus |
US20060132394A1 (en) | 2004-12-17 | 2006-06-22 | Canon Kabushiki Kaisha | Image display apparatus and television apparatus |
US20060132396A1 (en) | 2004-12-17 | 2006-06-22 | Canon Kabushiki Kaisha | Image display apparatus |
JP2006171502A (en) | 2004-12-17 | 2006-06-29 | Canon Inc | Image display apparatus and television apparatus |
JP2006195444A (en) | 2004-12-17 | 2006-07-27 | Canon Inc | Image display apparatus |
US7298094B2 (en) * | 2005-12-28 | 2007-11-20 | Canon Kabushiki Kaisha | Image display apparatus |
US20080150842A1 (en) | 2006-12-25 | 2008-06-26 | Canon Kabushiki Kaisha | Image display apparatus |
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